The US under Trump has woken the world into reality and the result in decades will certainly be a shit from the current US standing in the world, and that will be lovely.
I was an ardent supporter of the US until Trump came into power due to its role in the world. Trump only made me realise that it only takes a single leader to change the narrative and put the whole world in jeopardy. Tell me, is it bad for more than one country to have that power shared rather than being given to one (the US)? This is why EU should get itself together, they are also collectively capable. I don't know what's wrong with them.
Suppose China, the US, the EU, Russia etc. could have a powerful economic, political and military influence that can measure up against each other. In that case, it will rather cause a balance and mutual respect, and not the hopelessness as you view it. It mustn't always be the US.
I've also been sympathetic to USA since always, having that nation as standard of life quality, culture and organization.
I don't have a reason to sympathise with the US anymore, the world needs a bold step. Let there be power diffusion, it's better that way to checkmate tyranny and excesses.
I just think it would be pretty bad if a nation like China or Russia took charge of the world, due to their history of authoritarianism, manipulation and crimes (sometimes against their own people). And without USA, that is what inevitably would happen... EU doesn't have enough strength to fight from equal to equal against the eastern axis.
You sounded like the old me, but no more. Trump has opened my eyes to the possible tyrannical attitude of a US president if they choose wrongly. Who told you they can't still have a worse president than Trump in the future? The effect could be worse than your fear of China/Russia.
Also, what I advocate for is not for any country to have absolute power, but for about 5 of them having such a measure-up power to help in global stability, rather than seeing the US as the only worthy country.